Whether for the aura of serenity, or for being a pet that doesn't require long winter walks or messy litter boxes, fish of all shapes, sizes and colors have become a popular American pet.

There are hundreds of different kinds of fish that can be kept as pets. Goldfish are the most commonly-kept pet fish in the US because they can live in cold water.

Collectively, reptiles and amphibians are referred to as herps. That term comes from the Greek word herpes, which literally means crawling things. The term is applied equally to reptiles and amphibians. From herp comes herpetology, the study of crawling things. A person with formal training in herpetology is a herpetologist.